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Geastrum (orthographical variant Geaster)[1] is a genus of mushroom in the family Geastraceae. Many species are known commonly as earthstars.

Geastrum triplex.jpg
Geastrum triplex
Geastrum saccatum.jpg
Geastrum saccatum
Scientific classification

Type species
Geastrum coronatum

About 50; See text

The name, which comes from geo meaning earth and aster meaning star, refers to the behavior of the outer peridium. At maturity, the outer layer of the fruiting body splits into segments which turn outward creating a star-like pattern on the ground. The inner peridium is a spore sac. In some species, the outer peridium splits from a middle layer, causing the spore sac to arch off the ground. If the outer peridium opens when wet and closes when dry, it is described as hygroscopic.

In some species, the inner peridium is borne on a stalk or pedicel. The columella is a column-like clump of sterile tissue to be found inside the inner peridium. The network of fertile tissue inside the inner peridium, the capillitium, arises from the columella. The mouth in most species of "earth-stars" is quite prominent, often arising as a small cone at the apex of the inner peridium. It may be even or sulcate (grooved).[2]

They are generally not toxic but considered non-edible due to their fibrous texture in the mature stage at which they are generally found.


Although the Dictionary of the Fungi (2008) estimated roughly 50 species in Geastrum,[3] a more recent estimate (2014) suggests that there may be up to 120 species.[4] Geastrum coronatum Pers. has been proposed as the conserved type for the genus.[5] Some similar species that are otherwise difficult to differentiate using classical morphological features (such as G. triplex, G. saccatum, and G. lageniforme) can be identified using chemical spot tests that detect phenoloxidase enzymatic activity, as well as differences in the crystal structure of calcium oxalate deposits.[6] Species include:


  1. ^ Demoulin V. (1984). "Typification of Geastrum Pers.: Pers. and its orthographic variant Geaster (Gasteromycetes)". Taxon. 33 (3): 498–501. doi:10.2307/1220990.
  2. ^ Johnson MM. (1928). "The Gasteromycetae of Ohio". Ohio Biological Survey Bulletin 22. 4 (7): 271–352.
  3. ^ Kirk PM, Cannon PF, Minter DW, Stalpers JA (2008). Dictionary of the Fungi (10th ed.). Wallingford, UK: CAB International. p. 274. ISBN 978-0-85199-826-8.
  4. ^ Zamora JC, Calonge FD, Hosaka K, Martín MP (2014). "Systematics of the genus Geastrum (Basidiomycota, Fungi) revisited". Taxon. 63 (3): 477–97. doi:10.12705/633.36.
  5. ^ Zamora, J.C. "Proposal to conserve the name Geastrum (Basidiomycota, Geastrales) with a conserved type". Taxon. 63 (3): 679–680.
  6. ^ Zamora JC, Calonge FD, Martín MP (2013). "New sources of taxonomic information for earthstars (Geastrum, Geastraceae, Basidiomycota): phenoloxidases and rhizomorph crystals". Phytotaxa. 132 (1): 1–20. doi:10.11646/phytotaxa.132.1.1.
  7. ^ a b da Silva BDB, Cabral TS, Marinho P, Ishikawa NK, Baseia IG (2013). "Two new species of Geastrum (Geastraceae, Basidiomycota) found in Brazil" (PDF). Nova Hedwigia. 96 (3–4): 445–56. doi:10.1127/0029-5035/2013/0089.
  8. ^ Fazolino EP, Calonge FD, Baseia IG (2008). "Geastrum entomophilum, a new earthstar with an unusual spore dispersal strategy". Mycotaxon. 104: 449–53.
  9. ^ Cabral TS, Silva BDB, Ishikawa NK, da Silva Alfredo D, Neto RB, Clement CR, Baseia IG (2014). "A new species and new records of gasteroid fungi (Basidiomycota) from Central Amazonia, Brazil". Phytotaxa. 184 (4): 239–53. doi:10.11646/phytotaxa.183.4.3.
  10. ^ Domínguez De Toledo; Laura S. (1996). "Geastrum lilloi sp. nov. from Argentina". Mycologia. 88 (5): 858–62. doi:10.2307/3760982. JSTOR 3760982.
  11. ^ Kasuya T, Hosaka K, Uno K, Kakishima M (2012). "Phylogenetic placement of Geastrum melanocephalum and polyphyly of Geastrum triplex". Mycoscience. 53: 411–426. doi:10.1007/s10267-012-0186-z.
  12. ^ Douanla-Meli C, Langer E, Calonge FD (2005). "Geastrum pleosporus sp nov., a new species of Geastraceae identified by morphological and molecular phylogenetic data". Mycological Progress. 4 (3): 239–50. doi:10.1007/s11557-006-0127-3.
  13. ^ Cabral TS, da Silva BDB, Marinho P, Baseia IG (2014). "Geastrum rusticum (Geastraceae, Basidiomycota), a new earthstar fungus in the Brazilian Atlantic rainforest − a molecular analysis". Nova Hedwigia. 98 (1–2): 265–72. doi:10.1127/0029-5035/2013/0158.
  14. ^ Zamora JC, de Diego Calonge F, Martín MP (2014). "Combining morphological and phylogenetic analyses to unravel systematics in Geastrum sect. Schmidelia". Mycologia. 106 (6): 1199–211. doi:10.3852/14-072. PMID 25152001.
  15. ^ Cabral TS, Sousa JO, da Silva BDB, Martin MP, Clement CR, Baseia IG (2017). "A remarkable new species of Geastrum with an elongated branched stipe". Mycoscience. 58 (5): 344–350. doi:10.1016/j.myc.2017.03.004.